/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.buffer;

import io.netty.util.ResourceLeakDetector;
import io.netty.util.ResourceLeakTracker;
import io.netty.util.internal.ObjectUtil;

import java.nio.ByteOrder;

class SimpleLeakAwareByteBuf extends WrappedByteBuf {

  /**
   * This object's is associated with the {@link ResourceLeakTracker}. When {@link
   * ResourceLeakTracker#close(Object)} is called this object will be used as the argument. It is
   * also assumed that this object is used when {@link ResourceLeakDetector#track(Object)} is called
   * to create {@link #leak}.
   */
  private final ByteBuf trackedByteBuf;
  final ResourceLeakTracker<ByteBuf> leak;

  SimpleLeakAwareByteBuf(ByteBuf wrapped, ByteBuf trackedByteBuf,
      ResourceLeakTracker<ByteBuf> leak) {
    super(wrapped);
    this.trackedByteBuf = ObjectUtil.checkNotNull(trackedByteBuf, "trackedByteBuf");
    this.leak = ObjectUtil.checkNotNull(leak, "leak");
  }

  SimpleLeakAwareByteBuf(ByteBuf wrapped, ResourceLeakTracker<ByteBuf> leak) {
    this(wrapped, wrapped, leak);
  }

  @Override
  public ByteBuf slice() {
    return newSharedLeakAwareByteBuf(super.slice());
  }

  @Override
  public ByteBuf retainedSlice() {
    return unwrappedDerived(super.retainedSlice());
  }

  @Override
  public ByteBuf retainedSlice(int index, int length) {
    return unwrappedDerived(super.retainedSlice(index, length));
  }

  @Override
  public ByteBuf retainedDuplicate() {
    return unwrappedDerived(super.retainedDuplicate());
  }

  @Override
  public ByteBuf readRetainedSlice(int length) {
    return unwrappedDerived(super.readRetainedSlice(length));
  }

  @Override
  public ByteBuf slice(int index, int length) {
    return newSharedLeakAwareByteBuf(super.slice(index, length));
  }

  @Override
  public ByteBuf duplicate() {
    return newSharedLeakAwareByteBuf(super.duplicate());
  }

  @Override
  public ByteBuf readSlice(int length) {
    return newSharedLeakAwareByteBuf(super.readSlice(length));
  }

  @Override
  public ByteBuf asReadOnly() {
    return newSharedLeakAwareByteBuf(super.asReadOnly());
  }

  @Override
  public ByteBuf touch() {
    return this;
  }

  @Override
  public ByteBuf touch(Object hint) {
    return this;
  }

  @Override
  public boolean release() {
    if (super.release()) {
      closeLeak();
      return true;
    }
    return false;
  }

  @Override
  public boolean release(int decrement) {
    if (super.release(decrement)) {
      closeLeak();
      return true;
    }
    return false;
  }

  private void closeLeak() {
    // Close the ResourceLeakTracker with the tracked ByteBuf as argument. This must be the same that was used when
    // calling DefaultResourceLeak.track(...).
    boolean closed = leak.close(trackedByteBuf);
    assert closed;
  }

  @Override
  public ByteBuf order(ByteOrder endianness) {
    if (order() == endianness) {
      return this;
    } else {
      return newSharedLeakAwareByteBuf(super.order(endianness));
    }
  }

  private ByteBuf unwrappedDerived(ByteBuf derived) {
    // We only need to unwrap SwappedByteBuf implementations as these will be the only ones that may end up in
    // the AbstractLeakAwareByteBuf implementations beside slices / duplicates and "real" buffers.
    ByteBuf unwrappedDerived = unwrapSwapped(derived);

    if (unwrappedDerived instanceof AbstractPooledDerivedByteBuf) {
      // Update the parent to point to this buffer so we correctly close the ResourceLeakTracker.
      ((AbstractPooledDerivedByteBuf) unwrappedDerived).parent(this);

      ResourceLeakTracker<ByteBuf> newLeak = AbstractByteBuf.leakDetector.track(derived);
      if (newLeak == null) {
        // No leak detection, just return the derived buffer.
        return derived;
      }
      return newLeakAwareByteBuf(derived, newLeak);
    }
    return newSharedLeakAwareByteBuf(derived);
  }

  @SuppressWarnings("deprecation")
  private static ByteBuf unwrapSwapped(ByteBuf buf) {
    if (buf instanceof SwappedByteBuf) {
      do {
        buf = buf.unwrap();
      } while (buf instanceof SwappedByteBuf);

      return buf;
    }
    return buf;
  }

  private SimpleLeakAwareByteBuf newSharedLeakAwareByteBuf(
      ByteBuf wrapped) {
    return newLeakAwareByteBuf(wrapped, trackedByteBuf, leak);
  }

  private SimpleLeakAwareByteBuf newLeakAwareByteBuf(
      ByteBuf wrapped, ResourceLeakTracker<ByteBuf> leakTracker) {
    return newLeakAwareByteBuf(wrapped, wrapped, leakTracker);
  }

  protected SimpleLeakAwareByteBuf newLeakAwareByteBuf(
      ByteBuf buf, ByteBuf trackedByteBuf, ResourceLeakTracker<ByteBuf> leakTracker) {
    return new SimpleLeakAwareByteBuf(buf, trackedByteBuf, leakTracker);
  }
}
